import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.Set;

public class TimeClientHandler implements  Runnable{
    private String host;
    private int port;
    private Selector selector;
    private SocketChannel socketChannel;
    private volatile boolean stop;
    public TimeClientHandler(String host,int port){
        this.host = host;
        this.port = port;
        try {
            selector = Selector.open();
            socketChannel  = SocketChannel.open();
            socketChannel.configureBlocking(false);
        }catch (Exception e){
            e.printStackTrace();
            System.exit(1);
        }
    }
    public void stop(){
        this.stop = true;
    }

    @Override
    public void run() {
        try{
            doConnect();
        }catch (Exception e){
            e.printStackTrace();
            System.exit(1);
        }
        while (!stop) {
            try {
                selector.select(1000);
                Set<SelectionKey> selectionKeys = selector.selectedKeys();
                Iterator<SelectionKey> iterator = selectionKeys.iterator();
                SelectionKey key = null;
                while (iterator.hasNext()) {
                    key = iterator.next();
                    iterator.remove();
                    try {
                        handleInput(key);
                    } catch (Exception e) {
                        if (key != null) {
                            key.cancel();
                            if (key.channel() != null) {
                                key.channel().close();
                            }
                        }
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
        if (selector != null) {
            try {
                selector.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void handleInput(SelectionKey key)throws  Exception{
        if (key.isValid()) {
            SocketChannel socketChannel = (SocketChannel) key.channel();
            if (key.isConnectable()) {
                if (socketChannel.finishConnect()) {
                    socketChannel.register(selector,SelectionKey.OP_READ);
                    doWrite(socketChannel);
                }else {
                    System.exit(1);
                }
            }
            if (key.isReadable()) {
                ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                int readBytes  = socketChannel.read(readBuffer);
                if(readBytes > 0 ){
                    readBuffer.flip();
                    byte [] bytes = new byte[readBuffer.remaining()];
                    readBuffer.get(bytes);
                    String body = new String(bytes,"UTF-8");
                    System.out.println("the currentTime is "+ body);
                    stop();
                }else if(readBytes <0){
                    key.cancel();
                    socketChannel.close();
                }else {

                }
            }
        }
    }
    private void doConnect()throws  Exception{
        if(socketChannel.connect(new InetSocketAddress(host,port))){
            socketChannel.register(selector,SelectionKey.OP_READ);
            doWrite(socketChannel);
        }else{
            socketChannel.register(selector,SelectionKey.OP_CONNECT);
        }
    }

    private void doWrite(SocketChannel sc) throws  Exception{
        String REQUEST_ORDER = "ORDER";
        byte[] bytes = REQUEST_ORDER.getBytes();
        ByteBuffer buffer = ByteBuffer.allocate(bytes.length);
        buffer.put(bytes);
        buffer.flip();
        sc.write(buffer);
        if(!buffer.hasRemaining()){
            System.out.println("send order 2 Server successd.");
        }
    }
}
